Machine hydraulic systems may be utilized to drive one or more loads, such as propulsion of the machine itself, relative swing movement, or operation of a coupled arm or a work implement, either sequentially or simultaneously. In operation of such hydraulic systems, pump flow through a relief valve results in waste as fuel energy does not go to useful machine motion. Existing control strategies include a high pressure cutoff strategy, which sets the pump outflow pressure to the cracking pressure of the main relief valve. This high-pressure cutoff strategy only manages the energy loss across the main relief valve, however, leaving the remaining relief valves vulnerable to system waste.
U.S. Pat. No. 5,133,644 to Barr discloses a multi-pressure compensation arrangement that attempts to overcome this shortcoming. The pumping system of Barr includes a plurality of relief valve wherein each relief valve has a relief setting. A controller is configured to determine which relief valve is active, and then control the maximum pressure of a variable displacement pump based on the relief setting of the active relief valve.